In recent years, image forming apparatuses having composite functions including a printer mode, a fax mode, etc. in addition to a normal copying mode have been put into the market. In accordance with this trend, a post-processing apparatus which is attached to the digital image forming apparatus and functions as a mail box as well as a sorter has also been developed as commercial product.
In the case of a conventional post-processing apparatus, whether an error is made in a post-processed sheet is confirmed by an operator after the discharge of all the sheets. Thus, the conventional structure suffers from such a problem that a great deal of labor is required to confirm the occurrence of errors when the number of sheets to be discharged is great though the problem is not so serious when the number of sheets to be discharged is small.
In order to solve this problem, for example, a post-processing apparatus having a display function of displaying the post-processed state of sheets is described in Japanese Publication for Unexamined Patent Application No. 84549/1985 (Tokukaisho 60-84549) disclosing a "printing apparatus". The printing apparatus of this publication monitors the error state along with the processes of forming an image, and sorting and storing sheets performed by the image forming apparatus. When an error is detected in the output sheet, the position where the sheet having the error is stored is indicated. In this structure, when there is an error in the image information output on a sheet which has been sorted and stored in the post-processing apparatus, the position where the sheet is stored can be easily found.
As described above, the recent digital image forming apparatuses have various functions, such as fax and network printers. In such a digital image forming apparatus, it is common to use a post-processing apparatus such as a mail box for automatically separating the recorded matter to a bin provided for temporarily storing the recorded matter. The recorded matter usually contains information relating to the image corresponding to image data (image information data), i.e., various information such as the sender of facsimile, the name of data, and the name of client who output the data.
However, when a lot of recorded matter is output from the same image forming apparatus, it is difficult for an operator to find recorded matter addressed to the operator or recorded matter output to the bin by the operator itself. In particular, in the post-processing apparatus of a digital image forming apparatus having a plurality of bins, if the mail box is capable of variably changing the allotment of addressees, it is difficult to know which bin is to be searched.